Automatic musical instrument



APPLICATION FILED APR. 27, I920.

Patented Mar. 14, 1922 o vs ow awn mu vm 8 b wm ob oh UNITED STATES PATENT OFFICE.

CHARLES r. sronnann, on NEW YORK, N. Y., ASSIGNOR T0 AMERICAN PIANO COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

AUTOMATIC MUSICAL INSTRUMENT.

Specification Of Letters Patent.

Patented Mar. 14:, 1922.

Originalapplication filed December 9, 1913, Serial No. 805,488. Divided and this application filed April To all whom it may concern:

Be it known that I, CI-mmms F. STODDARD, a citizen of the United States, and a resident of the borough of Manhattan, city, county, and State of New York,have invented an Improvement in Automatic Musical Instruments, of which the following is a specification.

- This invention relates to automatic means for playing musical instruments such, for instance, as pianos; and pertains more parti :u lar-ly to means for'governing and varying tone intensities; this application being a division of an earlier application filed by me on December 9, 1913, Serial No. 805,488.

-Among other objects, the invention is intended to provide apparatus capable of pro ducing a great variety of variations in in tensity of playing, such apparatus comprising preferably, though not essentially, a combination of means for producing crescendo and decrescendo effects and also instituting various defined grades or steps of playing intensity. For these purposes the invention may be embodied in apparatus which is very simple and reliable in operation. v

For illustration, the accompanying drawingshows one practicable embodiment of theinvention employing suitable pneumatically governed'devices in cooperation with a piano action; but, as, will appear to those skilled in the art, the invention is susceptible of embodiment in various constructions and organizations other than that particularly shown and described herein. It will appear likewise, that it is not indispensible that all the features of the invention be used conjointly, since their respective substantial advantages may accrue, from their separate application in any practicable manner to a suitable playing instrument.

Inthe drawings:

Fig. 1 is a diagrammatic representation of a typical piano action, with operating and governing means exemplifying the application and utility of the invention;

Fig. 2 is a diagrammatic representation of a perforated note-sheet such as may be used in cooperation with the apparatus of Fig. 1.

Referring to the drawing, a typical piano action shown in its normal position of rest comprises a key-controlled sticker I3 to act Serial No. 376,908.

upon a wippen I, a hammer C, damper E,

string D and other parts which may be those well-known in the art. To operate the action pneumatically a motor pneumatic F is provided, having a sticker H to act upon the wippen I. A wind trunk 7 leads to the wind chest for the motor pneumatics, each of which has a secondary valve 8 controlled by a primary valve 9 operated from a tracker-board G through a duct 10, in the usual manner.

The trunk 7 communicates with a regulated exhaust chest 12, which may be of any practicable construction. A high exhaust chest 14., arranged for communication with the chest 12, may be connected by a trunk 15 with any source of pneumatic exhaust, such as feeder bellows of any practicable type.

For the purpose of explaining the general character of this invention, and to exemplify one practicable'manner of governing tone intensities, I have selected the apparatus of the drawings in which the striking pneumatics F are caused to operate by the regulated exhaust in the chest 12, the degree of this regulated exhaust being varied, in order to vary the operation of the striking pneumatics, by subjecting it more or less to the influence of the high exhaust in the chest 14. For these specific purposes I have pro vided, between the high exhaust chest 14 and the regulatedexhaust chest 12, a chamber 80, open at its lower extremity to the chest 14, and communicating with the chest 12 through suitable ports which are opened and closed in varying degrees by means of a throttle valve 31 governing communication between the two chests. For convenience, this valve 31 will be called a regulating valve.

This regulating valve 31 may be operated by a variety of different means; and as one practicable means for causing this valve to establish different substantially distinct grades or degrees of regulated exhaust in the chest 12, I have selected the valve governing apparatus shown and described herein. This illustrative apparatus comprises various tracker-controlled valve mechanisms, which I shall describe herein in order to illustrate how the same may be used in cooperation and combination with other features presented in this application.

In this specific apparatus the stem 32 of the regulating valve 31 rojects upwardly through the to of the c amber 30 into a cylinder of gra uated diameter. Within the cylinder is a unitary piston of graduated diameter corresponding in size and shape to the interior of the cylinder. Said piston comprises the three cylindrical parts 34, 35 and 36, presenting respectively the acting areas :19, y and z.

A tension spring 37 connected to the piston stem 32 may exert an upward pull upon the latter. By means hereinafter described the tension of the spring may be varied so as to modify its upward pull upon the piston structure; but for the present thiscapacity may be neglected and the upward pull of the spring may be considered substantially constant, disregarding the minute fluctuations in tension of the spring resulting from negligible elongation and contraction accompanying the slight movements of the piston structure. This substantially uniform pull of the spring contributes to control the piston structure and regulating valve 31, as presently described.

In discussing the various pneumatic influences brought to bear upon the piston structure, the so-called exhaust or air tension will be treated as having a positive pressure relative to a perfect vacuum of zero pressure. This mode of treatment is more convenient in explaining the operation of the piston structure than would be the case if exhaust were considered in the popular sense of exerting a pull bysuction, as distin uished from a push by pressure.

ucts 40, 41 and 42 enter respectively the cylinder chambers opposite the piston faces as, 3/ and 2. Each duct is controlled (as hereinafter explained) so as to admit to its cylinder chamber either atmospheric pressure, or regulated pressure from the chest 12 and the regulated pressure'may be admitted to any one or more, or all, of the chambers while atmospheric pressure will be present in those chambers if any,'which do not contain regulated pressure. These pressures within the cylinder chambers act upwardly upon the piston faces w, y and .2, and together with the upward pull of the spring 37, constitute the forces tending to move the piston structure upwardly. The hi h exhaust in chest 14 exerts some upwar pressure upon the piston valve 31, which is so minute as to be negligible in the specific apparatus under discussion.

These upwardly directed forces are opposed by whatever pneumatic pressure may act downwardly upon the piston structure; and for the present it may be assumed that atmosphere is constantly pressing downwardly upon the upper faces of the piston structure, being admitted thereto through a vent 33 conveniently provided by a clearance around the piston stem 32 in the cover plate of the cylinder. As hereinafter described, the pneumatic condition in the upper chamber of the cylinder and acting downwardly upon the upper faces of the piston, may be varied by exhausting the same more or less, but the explanation thereof may be deferred. 1

In the illustrative apparatus the upwardly exposed piston areas substantially equal the downwardly exposed areas m, g and a. If, therefore, atmosphere be admitted to all the cylinder chambers, its upward pressure on the areas 2:, y and 2 will be opposed and balanced by equal downward pressure of atmosphere upon equal areas. This leaves the spring 37 unopposed to lift the piston valve 31 and open the valve ports to the fullest extent thereby subjecting regulated pressure in the chest 12 to the maximum influence of high exhaust in the chest 14. Under these conditions notes are sounded with maximum loudness.

When the present invention is embodied in a construction which employs exhaust as distinguished from compressed air, the regulated exhaust or pressure is always less than atmospheric pressure. Consequently when regulated pressure is admitted to all the cylin er chambers, the upward pneumatic pressure on the piston structure is then at its minimum, being, of course, less than when atmosphere is admitted to any one or more of the cylinder chambers. Downward atmospheric pressure, being in such case opposed by the minimum pneumatic upward pres sure, substantially predominates and presses the piston structure downwardly, the spring 37 having its tension adjusted so that its upward pull may be overcome more or less by said downward atmos heric pressure. This downward tendency o the piston structure may close somewhat valve ports between the chests 12 and 14 with the result that regulated pressure may be materially cut off from the influence of high exhaust in the chest 14. Under these conditions, i. e. when regulated pressure is admitted to all the cylinder chambers, notes are played with minimum loudness available in the specific apparatus illustrated in the drawings.

It will be evident to those skilled in the art, that the greater the piston area exposed to regulated pressure, the greater will be the predomination of downwardly acting atmospheric pressure and the greater will be the tendency to constrict communication between the chests 12 and 14. In other words, the greater the piston areas exposed to regulatedpressure, the less is regulated. pressure subjected to the influence of high exhaust and the less will be the intensity of sounded notes. Accordingly, the general operation of the cylinder and piston structures described above may be conveniently summarized thus :admitting regulated pressure to a cylinder chamber diminishes intensity; admitting atmospheric pressure to-a cylinder chamber increases intensity.

There is always some leakage of atmosphere to the chest 12- as, for instance, past the various valve mechanisms and from the motor pneumatics, such leakage tending constantly to increase regulated pressure and actually increasing it unless the leakage be fully compensated byexhaust through the chest 1 1- by'way of the valve ports in the chamber 30. Under these circumstances, whenever the piston structure moves down wardly and thereby restricts the openings between the. chest 12 and 14., the result is to increase regulated pressure. This increase in regulated pressure is, of course, communicated practically instantaneously to those cylinder chambers which contain regulated pressure. Consequently, whenever the piston structure moves downwardly, the indirect result is to increase the upwardly acting regulated pressure and thereby to decrease, the predominance of downward atmospheric pressure. The greater the extent of downward movement of "the piston structure'the greater will be the described decrease in thepredominance o f downward atmospheric pressure.

In any instance the piston structure will move downwardly until the predominance of downward atmospheric pressure diminishes to such an extent that the upward pull of. the spring balances such diminished predominance, whereupon the piston structure comes to rest balancedbetween the opposed forces, H

In like manner, whenever the piston structure moves upwardly to enlarge the openingsbetween the chests 12 and 14, the eitect is to diminish regulated pressure by exhaust through the chest 14. This diminution in regulated pressure is communicated to those cylinder chambers which contain regulated pressure and consequently the upward reg ulated pressure on the piston is diminished. In other words. the piston structure moves upwardlybecause ofthe predominance of upward pneumatic pressure plus the pull of the spring; such upward movement of the piston structure has the efliect of decreasing the predominance of upward pressure and such. decrease continues during upward movement of the piston structure until there is no longer any predominance and the opposed Forces are again balanced. whereupon the piston structure comes to rest.

In theoperation of the specific illustrative apparatus, therefore. the piston structure is constantly under the control of opposed forces tending always to balance each other and hold the piston structure. it were. in suspension between them: that is to say. the specific apparatus tends constantly to establish a balancing equation between the opposed forces acting upon the piston. Such movement of the piston structure as may occur when that balancing equation is disturbed, takes place practically instantaneously so that a new balancing equation appropriate to the newly initiated conditions 18 immediately set up.

The actual variation of regulated pressure may result from a numberof causes, or a combination of causes, such that the piston structure and valve 81 may or may not be moved to assist in a re-establishment of the pressure equation above referred to, which holds the piston structure in balance.

Normally, and even at a time when it is desired to maintain constant regulated pressure, some leakage of atmosphere to the chest 12, and various parts communicating therewith, may tend to reduce the regulated tension in said chest, whether or not any of the motor pneumatics F is in action. A reduction in regulated tension from such cause may be compensated to some extent by leakbetween the high tension chest 14 and the chest 12. as by leakage past the piston valve 31. 11, however, regulated pressure increases enough to disturb a prevailing pressure equation, there may result an upward movement of the piston structure, enlargin the openings between the chests 12 and 142 enough to permit high exhaust to restore the intended regulated pressure in chest 12. Such action takes place so promptly and q uickly, that, in effect, it serves to maintain regulated tension substantially constant (until intentionally adjusted), rather than to restore it.

Each motor pneumatic F, when idle, contains atmosphere which tends to increase regulated pressure in the chest 12. when the pneun'iatic is thrown into operation. Obviously. it several motor pneumatics F act simultaneously there may be a considerable increase of regulated pressure. Ordinarily. in the operation of the illustrative apparatus. the regulated pressure may be thus subjected to frequent fluctuations by the action of the motor pneumatics. Whenever such fluctuation so increases regulated pressure that a pressure equation is disturbed, the piston valve 31 may be moved to restore the equation as described. As already suggested. this restoring action takes place so quickly that it is rather a maintaining action in respect to its general effect upon the regulated pressure.

From the above it appears that whatever dra'lt are made upon the regulated pressure chest and "from whatever cause. said pressure mav be maintained always by the described balancing operation of the piston structure controlling; communication beween the chests 12 and 14;. lmn ediatel v. however, when a deliberate, intentional ch.nge is made in the piston area exposed to regulate pressure, the pressure equation is temporarily disturbed, to be restored when a new and different regulated pressure is established.

It will be noted that the regulating action of the piston structure may serve merely to maintain the desired regulated pressure in spite of any drafts made thereupon, as for instance, by the motor pneumatics. That is to say, the regulation does not necessarily result from varying communication between the high exhaust chest and the regulated pressure chest. For instance, assume that the piston area acted upon by regulated pressure be so changed that a considerable increase in regulated pressure is demanded to rc-establish the pressure equation. Assume further that this change in piston area be accompanied by the action of a considerable number of motor pneumatics F, whichin effect alone sufiices to increase the regulated pressure so as to re-establish the balancing pressure equation. Under such circumstances regulated pressure is changed from a lower to a higher working level without making necessary any change in the commmiication between the two chests 12 and 14. 'Thus in greater or less degree, the work done by regulated pressure in the chest 12, may cooperate with the deliberate variations of piston area acted upon by the regulated pressure, so that the control of communica tion between the chestsexercised by the piston valve may be, and frequently it will be, of merely supplemental and auxiliary effect.

l-lereinbefore, a preferred form of regulating mechanism has been described. The manner in which the same may be governed to initiate different substantially distinct grades of regulated tension will be next explained. V

, Referring again to the drawing, the duct 40 connects the cylinder chamber opposite the piston area m with a valve chamber 49. In said chamber is a duplex valve 50, arranged for opening an upper port to atmosphere and alternatively opening a port from the chamber 49 through a duct 51 to the regulated tension chest 12. The valve 50 is controlled by a diaphragm over a chamber 54 which communicates with a duct 56. A duplex valve 58 controls a port from the duct 56 to atmosphere. and a second port, from the duct 56 to a chamber 59 communicating by a duct 60 with the high pressure chest 14. The valve 58 is controlled by a diaphragm over a chamber 62 which communicates by aduct (33 with a tracker vent T.

\Vhen the tracker vent T is open the diaphragm of chamber 62 and the valve 58 are elevated soas to vent the diaphragm chamber 54 to atmosphere and lift its diaphragm and the valve 50 and vent the duct 40 to atmosphere. The converse of this operation which closes the duct 40 to atmosphere and opens it to regulated tension, will be described hereinafter.

The parts just described are triplicated for controlling the ducts 41 and 42, the corresponding parts of the valve mechanism for the latter being indicated by the numerals 50, 51, etc., with indices a for the valve mechanism for duct 41, and b for the valve mechanism for duct 42.

I11 the valve mechanism for duct 41 it is assumed that the duct 63 to the tracker vent T is open to atmosphere which lifts the diaphragm of chamber 62*, venting chamber 80 54 to atmosphere and admitting atmosphere to the duct 41, past the valve 50F and to the cylinder chamber opposite the piston surface y. Thus, whenever a tracker vent T, T or T is open, atmosphere is admitted to the corresponding cylinder chamber.

When one of the valves 50, 50, 50", is once opened by venting the corresponding tracker duct, the valve preferably continues open even though the tracker vent may be immediately closed. In the specific apparatus this results from the fact that once the valve 58, for instance, is opened to admit atmosphere to the diaphragm chamber 54*, said valve 58 is held in that position by atmosphere admitted past the valve 58 into a duct through a bleeder vent 72, and a duct 74 (shown in dotted lines), which latter communicates with the diaphragm chamber 62'. The chamber 59 above the diaphragm communicates as described with the hi 'h exhaust chest 14. Thus, so long as atmos here is admitted through duct 70 to duct 4 the diaphragm of chamber 62 will remain lifted and atmosphere will continue in the corresponding cylinder chamber 3 The parts just described as pertaining to the valve 50' are duplicated to cooperate with the valves 50 and 50".

From the preceding discussion it will ap- 110 pear that small perforations in a music sheet may be employed to open the tracker vents T,

T and T which may be immediately closed if desired. When used with the illustrative apparatus, each such perforation has the ef- 116 fect of introducing atmosphere to a cylinder chamber,.and even after the tracker vent is closed, atmosphere will continue in the cylinder chamber until purposely exhausted at any desired subsequent time in a manner 120 such as that about to be described.

The specific apparatus shown in the drawings, comprises a single valve mechanism, controlled by a single tracker vent, which may cooperate with all or any of the three 125 above described valve mechanisms, to negative the effect of opening one or more of the tracker vents T, T and T". This single valve mechanism is shown at the right of Fig. 1.

A tracker vent R communicates by its duct 80 with a diaphragm chamber 82. The latter controls a duplex valve 84 which in its alternative positions admits atmosphere to a duct 86 or opens communications between said duct 86 and a duct 88 leading to the high exhaust chest 14. An extension of th duct 86 communicates with each of the three diaphragm chambers 90, 90? and 90 Thus when atmosphere is admitted to the duct 96, past the valve Set, the diaphragms of the chambers .90, 90 and 90 are lifted. In describing the effect of this operation, it is convenient to refer to chamber 90 and associate parts.

As already stated, the valve 58 is held in the open position shown, because atmosphere is present in the ducts and 74*. When, however, the diaphragm of chamber 90 is lifted, it lifts a disk valve 92 and closes communications between duct 70 and duct 74, thereby closing the latter from atmosphere. At the same time the valve 92 opens communication between the duct 74? through the bleeder 72, with chamber 94* which is open to high exhaust through the duct 60*. In this manner the duct 74 is connected with high exhaust which bleeds the atmosphere from chamber 62 thereby permitting valve 58 to drop, shutting off atmosphere from the diaphragm'chamber 54 and throw ing the latter into communication with the chamber 59 and the high exhaust chest 14: through the duct 60 When the diaphragm chamber 54? is thus exhausted by high exhaust, the valve 50 is permitted to drop shutting off atmosphere from the cylinder duct 41 and throwing the later into .communication with the duct 51 leading to the regulated pressure chest 12. In this manner, by opening the tracker vent R, the duct 41 and its cylinder chamber 7 are closed to atmosphere and opened to regulated pressure.

The operation just described, so far as concerns the specific illustrative mechanism, depends upon bleeding the diaphragm chamber 62. If the tracker duct 63 be open through its vent T. at the time the vent R is opened to initiate the bleeding of diaphragm chamber 62% atmosphere will enter the chamber 62 more rapidly than it can be exhausted therefrom by the described bleeding; therefore, the effect of opening the vent R is negatived, and in such circumstances that valve 58 will remain open and atmosphere will continue in the corresponding cylinder chamber.

Also, if the tracker vent T. for instance, be open simultaneously with the tracker vent R, the latter will inaugurate a tendency to bleed the chamber 62 and keep the valve 558 closed inthe position shown, but the simultaneous opening of the tracker vent T will admit atmosphere to the chamber 62 more rapidly than it can be exhausted by bleeding and therefore the valve 58 will be lifted in spite of the opening of the tracker vent R.

From the above description it will be understood that Whether or not the tracker vent R be open, the opening of any of the vents T. T, T, will have its normal and usual effect to admit atmosphere to the appropriate chamber or chambers of the cylinder. This will be true if any vent T, T, T", be opened with or without simultaneously opening the tracker vent R.

On the other hand, if the vent T be opened and then closed (atmosphere being thereby admitted to a cylinder chamber) and the vent R- be thereafter opened, the previous effect of opening vent T will be negatived and the cylinder chamber opened to regulated pressure.

The effect of opening and closing the various tracker ducts in the specific mechanism may be readily understood by referring to an illustrative form of perforated music sheet diagrammed in Fig. 2 in which are shown four lines of perforations at the left for governing the above described expression controlling tracker vents. The music sheet may be assumed to be travelling in the direction of the arrow in Fi 2. The tracker G is shown in dotted lines in 2, the vent T being open through the perforation 300 in the sheet. All the other vents are closed. The perforations in the sheet for operating the motor pneumatics may be disregarded for brevity.

hen the note sheet and tracker are related as shown in Fig. 2, the various valve mechanisms occupy exactly the positions shown in Fig. 1. If new the music sheet progresses in the directionof the arrow, perforation 301 will presently open the vent R; this will lift the diaphragm of chamber 82; open the duct 86 to atmosphere; admit atmosphere to diaphragm chamber 90; lift valve 92; and throw the diaphragm chamber 62? into communication with the high exhaust chest 14, through the duct 7%, past the bleeder 72, through the chamber 94 and duct 60 This permits the valve 58 to drop and thereby the diaphragm chamber 54 is exhausted as described, with the final result that the cylinder duct ll and chamber 7 are closed to atmosphere and opened to regulated pressure. In these circumstances regulated pressure is present in all of the cylinder chambers.

lV-hen the music sheet progresses further, the perforation 302 opens the vent T and, as will'be understood, thereby opens the duct 40 and cylinder chamber a: to atmosphere. Thereafter a perforation 303 and. a perforation 304 register respectively and simultaneously with the vents R and T. The perforation 303 negatives the previous effect ofcthe perforation 302 and opens the cylinder ch amber foratl on .r to regulated pressure. The per- 303 is ineffective, however, in respect to perforation 304 which opens the vent T and thereby admits atmosphere to the cylinder chamber y As the note sheet progresses further, perforations 305 and 306 open the vents T and T which admit atmosphere to the cylinder chambers 02 and e. The previous effect of the perforation 304 endures, and therefore by reason of the three perforations 304, 305 and 306, atmosphere is present in all of the cylinder chambers.

Next a perforation 307 opens the vent R and simultaneously a perforation 308 opens the vent T. The effect of the perforation 307 is to negative the previous effect of both the perforations 305 and 306 and to open the cylinder chambers 50 and .2 to regulated pressure. The perforation 307, however, is ineffective in respect to perforation 308 which merely continues the previously established effect of the perforation 304 leaving the cylinder chamber 1 still opento atmosphere.

Next perforations 309 and 310 reinstate atmosphere in the cylinder chambers 00 and e, and again all of the cylinder chambers are open to atmosphere.

Next a perforation 311 opens the vent R at a time when all the other vents are closed, and thereby negatives the effects of all three perforations 308, 309 and 310, with the re sult that all the cylinder chambers are closed to atmosphere and open to regulated pressure.

The preceding description will suffice to indicate the variety of combinations of perforations whereby atmosphere and regulated pressure maybe alternated in one or more of the cylinder chambers with the resultant variations in regulated pressure and in the intensities of notes played thereby.

As will appear to those skilled in the art, the usual note perforation may occur in the music sheet or maybe relatedwith the described expression-regulating perforations, in any practicable manner, as for instance by aligning or substantially aligning the advance end of a note perforation with one or more expression perforations to establish the regulated pressure in the chest 12 for playing the note with the desired intensity.

The preceding description has been de voted to an illustrative form of apparatus by which substantially distinct grades or degrees of regulated exhaust may be established for playing notes with substantially distinct grades of intensity, each such grade being louder or softer than the next grade by a more or less definite and considerable increment. Such an apparatus may be employed to advantage in conjunction with a so-called crescendo and diminuendo apparatus next to be described; but the illustrative form of the latter shown in the-drawings, is likewise susceptible of being used separately, and it will be first explained as used independently of all the other apparatus except the illustrative valve 31, which exemplifies means for controlling and varying theregulated exhaust in producing crescendo and diminuendo effects. In this connection, it will be assumed for the present that the pneumatic conditions in the respective cylinder chambers, opposite the piston faces x, 7 and z, are maintained constant during operation of the crescendo and diminuendo apparatus, as by having regulated exhaust present in each said chamber. Under this assumption, therefore, atmosphere pressing downwardly on the piston structure predominates over regulated exhaust pressing upwardly, the result being a tendency to hold the piston structure and valve 31 down against the pull of the spring37 to cause the notes to be played with minimum intensity.

For the purpose of the illustrative crescendo and diminuendo apparatus, the spring 37 is connected as shown to the movable board 150 of a pneumatic 38, which is supported in any practicable manner and provided with a stop 151, against which said movable board normally rests under the pull of a spring 152 which tends to hold the pneumatic distended.

A port 153 is provided in a fixed board of the pneumatic 38, and from this port a duct 154; leads to a passage 155 passing through the wall of a casing 156. This casing is formed with a plunger chamber 157 in which a plunger 158 is adapted to work. ()no end of the plunger chamber is enlarged to form a cylinder 159 in which works a piston 160 firmly secured to the corresponding end of the plunger 158. The cylinder is closed by a cap 161 secured thereto in any suitable manner as by being screwed thereon. The open end of the piston chamber 157 may be closed by a screw threaded plug 162. A spring 163 mounted in the plunger chamber 157 tends to move the plunger outwardly, or to the right in Fig. 1, and by means of a valve the chamber 157 may be placed alternatively. in communication with atmosphere or with high exhaust. While any suitable valve construction may be used for this purpose, it has been found convenient to use a valve construction of the ball type (Fig. 1) comprising the passage 165 leading from the chamber 1 7 to atmosphere, the passage 166 leading from said hamber to an exhaust chamber 167 provided within the wall of the casing. and the valve member 168 fixed to one end of a rod 169 that passes loosely through said passage 166, said rod 169 being attached at its other end to a piston 170 that works in a cylinder 171 closed by a screw threaded cap 172. The exhaust chamber 167 communicates with the chamber of the cylinders 159 and 171 and also by a duct 173 with a source of high exhaust, which may be the chest 14. The passage 155 communicates normally by a passage 175, of less diameter, with an annular recess 176 provided in the outer surface of the plunger 158 and this annular recess communicates with the plunger chamber 157 by means of the passages 177 and 178.

The cylinder chambers 159 and 171 communicate by ducts 180, 181 with vents 182, 183, respectively, provided in the tracker.

From the construction described, it will be apparent that with the parts in the positions indicated in Fig. 1, the pneumatic is in communication with atmosphere by means of duct 154:, passages 175, 176, 177, 178, chamber 157 and passage 165, it being assumed that the vents 182, 183 are closed, so that high exhaust exists upon both sides of the pistons 160 and 170, and the passage 166 is closed by the valve member 168. The pneumatic 38 is thus in extended position. If the vent 183 be opened, for instance by a perforation in a note sheet, atmosphere will be admitted to the cylinder chamber 171 and piston 170, and the valve member 168 will be moved to close the passage 165, and open the passage 166, thus cutting off the pneumatic from atmosphere and placing it in communication with high exhaust in chamber 167.

This tends to collapse the pneumatic 38, but owing to the relatively small diameter of the passage 175, the exhaustion of the pneumatic is retarded. With this arrangement, if the tracker vent 183 is open for only an instant, the effect in collapsing the pneumatic 38 is only slight; if the tracker vent 183 be held open for a substantial period, oris opened a number of times in moreor less rapid succession, the effect is to cause a. substantial collapse of the pneumatic 38 which, ho'wever,.takes place slowly because of the relatively small diameter of the passage 175.

If the vent 183 be open continuously for a time, the pneumatic 38 will collapse slowly at substantially uniform speed, thereby uniformly increasing the tension of the spring 37. It has been seen heretofore that the tension of the spring 37 constitutes one of the forces controlling the piston structure and regulating valve 31; hence, as the pull of the spring is increased as described, the

balance of the regulating forces acting on the valve is disturbed and the upward pull increasingly predominates, thereby tending to enlarge gradually the communication between the chests 12 and 14: and to give an excellent crescendo effect.

. When the tracker vent 183 has been open for a suflicient length of time, or a suflicient number of times in succession, to cause a substantial collapse of the pneumatic38, the subsequent closing of the vent 183 shuts off the atmosphere from the cylinder chamher 171, which is thereupon promptly exhausted by leakage around the piston 170, so that the valve member 168 is returned by gravity to the position shown in Fig. 1 and atmosphere is admitted to the plunger chamber 157 through the passage 165. This atmosphere gradually leaking into the interior of the pneumatic 38 past the passage 17 5 of relatively small diameter permits the pneumatic to be expanded gradually by its spring 152, the speed of this expansion of the pneumatic being retarded by the relatively small diameter of the passage 175. As the pneumatic is thus gradually expanded, the pull on the spring 37 is gradually relaxed, thereby gradually decreasing the upward pull on the piston structure and permitting the forces controlling the latter to resume a balanced relation. Obviously, the efl'ect of this operation is to reduce gradually the predominance of upwardly acting forces on the valve and thereby produce a decrescendo.

So long as the vent 183 is held continu ously open, the result will he gradually increasing regulated exhaust, the increase being to all intents and purposes continuously progressive, as distinguished from a progression by substantially distinct increments or steps provided for by the first described valve mechanism for controlling the pneumatic conditions within the graduated cylinder. This provides for what I consider a theoretically perfect crescendo, in which each note played during the course of the crescendo is given an intensity determined by that point of time in the duration of the uniformly progressive crescendo at which the note is played. This applies likewise to the diminuendo, in which, by the described apparatus, each note is given that intensity which corresponds to the time in the diminucndo period at which the note is played.

Of course, the highly refined effect just described is desirable as contributing to an ideal rendition, and especially as assisting in the faithful reproduction of the delicate nuances of great artists. For many commercial purposes, however. such refinement is not necessary.

In addition to the continuously progressive crescendo which may be produced as above described, a similar (though not so highly refined) effect will be produced by collapsing the pneumatic 38 in progressive steps. For instance, the tracker vent 183 may be opened a number of times in succession by a series of small perforations spaced apart so as not to have the effect of a single continuous perforation but to provide an intermission in the collapse of the pneumatic 39 between each perforation and the next succeeding one. During each such intermission, the pneumatic 38 tends to re-expand, but this expansion is so retarded by the relatively small. diameter of the passage 175 that, if it occurs, it is so slight as to be immaterial when the intermission is short. If the perforations of the crescendo series are placed close together, they cause the collapse of the pneumatic 38 to occur in a rapid succession of steps, while if such perforations are placed further apart, the collapsing steps of the pneumatic follow each other less rapidly and the crescendo is more gradual. Thus the speed of collapse, that is to say, the rapidity of the crescendo, may be determined auto matically as by the described variations in the spacing of crescendo perforations in the note sheet. Of course, the crescendo perforations may be placed so close together in relation to the size of their tracker vent as to give the effect of a single long perforation which will produce the continuously progressive crescendo hereinbefore referred to.

A diminuendo by progressive steps may be provided for in a manner similar to that above described in connection with the crescendo. For example, the pneumatic 39 having been partially collapsed and the tracker vent 183 thereafter closed, the pneumatic 38 begins to expand by reason of the atmosphere admitted past the passage 175. If during this expansion the vent 182 be open temporarily, the expansion of the pneumatic 38 is temporarily arrested with a tendency to cause a slight collapse. The vent 182 being then promptly closed, the expan sion of the pneumatic 38 is resumed, and so on, as many interruptions to the diminuendo being introduced as may be desired to delay or prolong the diminuendo.

The duration of a crescendo period may depend obviously upon the length of time that the tracker vent 183 is maintained open and the duration of a diminuendo period will depend upon the time consumed by the pneumatic 38 in expanding from whatever position of collapse it may have occupied at the end of a preceding crescendo. The rapidity of the crescendo or diminuendo, that is to say, the extent of increase or decrease in intensity in a unit of time, will depend upon the capacity of the communication between the pneumatic 38 and the source of high exhaust or atmosphere, respectively; and by varying such communication at any suitable point, thereby varying the speed of collapse and expansion of the pneumatic 38, the rapidity of the crescendo or diminuendo can be varied. Means for accomplishing this result are exemplified herein by the plunger 158 and its cooperating parts, as will now be more fully described.

With the parts in their respective positions shown in Fig. 1, if the vent 182 be uncovered, atmosphere will be admitted to the cylinder chamber 159, and the piston 160 with its plunger 158 will be moved inwardly or to the left, in Fig. 1, against the tension of the spring 163 until both the passage 155 of relatively larger diameter and the passage 175, communicate with the annular recess 176 of the plunger 158. The communication between the pnematic 38 and the source of high exhaust will thus be enlarged. If, then, the vent 183 be uncovered then a crescendo will be initiated; and the crescendo thus produced will be more rapid than the crescendo heretofore described as produced when the passage 175 was the sole. means of communication between the duct 154 and the annular recess 176 of the plunger 158. If the vent 183 has already been opened before the vent 182 is uncovered, so that a crescendo is already in progress at the time that the movement of the piston 158 to the left, Fig. 1, takes place, then the more rapid crescendo due to the uncovering of the vent 155 will be simply superposed on the crescendo already initiated by the uncovering of the vent 183, the more rapid crescendo starting from the point reached by the slower crescendo at the time that the vent 182 is uncovered.

It will be apparent that the more rapid crescendo will continue so long as both the vents 182 and 183 remain open. Both said vents being open, if the vent 182 onlybe closed, thus permitting the cylinder chamher 159 to be exhausted by leakage around the piston, the plunger 158 will be returned to the position represented in Fig. 1, by the action'of the spring 163, so that com- 100 munication between the duct 154 and the annular space 176 of the piston will be limited to the passage 175 only. It is obvious that the more rapid crescendo produced by opening both vents 1.82, 183 will thus cease upon 105 the closure of the vent 182; but that, the vent 183 still being open, the slowcrescendo will continue from that point. If then the vent 183 be closed. also, the slow diminuendo will result and continue until the pneu- 110 matic 38 is completely inflated.

If both vents 182, 183 be open, the apparatus thus producing the fast crescendo, as already describedand the vent 183 be then closed while the vent 182 remains open, a. 115 rapid diminuendo will be produced. This will continue until the pneumatic 38' is completely inflated-unles the operation'is interrupted in the meantime as, for example, by closing the vent 182, in which case the 120 plunger 158 will resume theposition represented in Fig. 1 and during the remainder of the time necessary to the complete inflation of the pneumatic 38, the slow diminuendo will continue.

The regulation of playing intensity in substantially distinct steps and the creation of crescendo and decrescendo effects may be combined with great advantage.

For example, the Valve mechanism con- 180 trolled by the vents T, T, T" and B may determine the starting point, in the scale of intensities, of a crescendo or a diminuendo whereby a crescendo or a diminuendo may be superposed as it were upon an already existing intensity regulation determined by the previous opening of one or more of the vents, T, T, T and R.

' Either the slow crescendo produced by opening the vent 183 alone, or the rapid crescendo produced by causing both vents 182 and 183 to be opened may be superposed upon an already existing intensity regulation. In thesame manner the rapid crescendo may be superposed upon a slow crescendo by first opening the vent 183 and thereafter opening the vent 182; or both said vents being open, the slow crescendo and proceeds from that, I will be no may be superposed upon the rapid crescendo by causing the vent 182 to be closed, the vent 183 remaining open.

Similarly, a more rapid diminuendo may be superposed upon an already existing slower diminuendo, or vice versa. Furthermore, as will appear to those skilled in the art, the play ing intensity may be increased by a sudden practically instantaneous step superposed upon a crescendo which is in progress, thereby, for example, particularly emphasizing some note or notes in the crescendo. Such effects and many others may be produced by appropriately combining the crescendo and diminuendo effects with the increasing aiid decreasing of l11iG11 sitiesby the distinct stops; it is, however, deemed. unnecessary to describe these various different combined effects, in any greater detail, since they will be readily understood by those skilled in the art.

In Fig}. 2 the arrangement of a perforated music sheet for producing some of these combined effects, is shown for illustration. For instance, a perforation 315 is provided for opening the tracker duct 183 to produce a slow crescendo, followed, when the vent 183 is again closed, by slow decrescendo. As already describedgthe perforation 311 in the music sheet has had the effect of introducing regulatedpressureto all of the cylinder chambers a2, y and z, and therefore the slow crescendo caused by the perforation 315 starts at the lowest level of playing intensity and proceeds from that 'level'so long as the perforation 315 continues, and then returns to the lowest level of intensity. Thereafter, a perforation 316 opens th tracker vent T thereby admitting atmosphere to the cylinder chan her .r and cansing the instrument toplay louder by a distinct step. Nhen, therefore, the perforations 31?" and 3 18 start a fast crescendo, the latter begins at a louder level ofQl;

thatthe perforation 318 controll speed of operation of the pneumatic 38, e31

tends beyond the rear end of the perforation 317 so that the combined effects of the perforations 31'? and 318 produce a fast crescendo so long as the former acts, following by a fast decrescendo. Thereafter, a perforation 319 starts a slow crescendo during which it may be assumed for illustration, it is desired to emphasize some note or notes by introducing an increase in playing intensity by a distinct step, and immediately thereafter: eliminating this increase to permit the crescendo to continue without further emphasis.

lVhile the slow crescendo caused by the perforation 319 is in progress, two perforations 320 and 321 introduce atmosphere to the cylinder chambers y and 2 and this combining with the effect of the perforation 316 causes the loudest playing to ensue. Shortly thereafter, however, the perforation 322 negatives the effect of the perforations320 and 321 while the perforation 323 continues the previous effect of the perforation 316 so that the level of intensity upon which the crescendo started is restored, and the crescendo continues so long as perforation holds the vent 183 open. As will appear to those skilled in the art, the effect of the perforations 320 and 321, followed more or less promptly by the perforations 32:2 and is to select a certain stage in the crescendo at which notes will be particularly emphasized above the intensities which they would otherwise have in the crescendo at that time.

For further illustration, a perforation 324 starts a fast crescendo during the progress of the slow crescendo by the perforation 319, and after the latter perforation has terminated, the prolongation of the perforation 324 causes a fast decrescendo. If the )(Blf'ftflkilfill 32% be terminated before the nicumatic 33 has had time to expand to the fully open position. then the remaining expansion, after the perforation 324 has passed the tracker, results in a slow decrescendo to the level of intensity determined by the perforation 323.

The foregoing will sutlice to illustrate the various combined arrangements of intensity-step controlling perforations, and crescendo and diminuendo perforations, by which a great variety of effects may be produced as will. appear to those skilled in the art.

hen it is desired to provide for controltensities more or less manually, in

itution or supplementation of the de- 1 i'oed preferably automatic devices, some such manual arr gement may be used as t-iiat shown in the d awings and exemplified by a push button 2-00. The illustrative button may be mounted in any practicable position on the instrument, as for instance, in the key bed within easy reach of the operator, and it is preferably mounted to move vertically under pressure, being sustained in normal position by a spring 201. The lower end of the button is provided with a valve cooperating with a seat preferably to produce a graduated opening between a duct 202 leading to a source of exhaust, preferably high exhaust, and a duct 203. The

' duct- 203 preferably communicates With the interior of the expression cylinder opposite the upwardly exposed faces of the piston. A bleeding vent 204 may be provided in the button 200 so as'to admit atmosphere normally to the interior of the cylinder. When, however, the operator places his finger upon the top of the button, this bleeding vent is closed. On depressing the button 200 communication is opened with a gradual, or rapid increase, depending upon the speed of depression of the button, between the exhaust duct 202 and the duct 203. In this manner exhaust may be introduced to the interior of the cylinder to modify the pneumatic conditions therein and thereby to vary the differential of the pneumatic pressures acting upwardly and downwardly on the piston to control the throttle valve 31. As will appear to those skilled in the art, an arrangement such as that exemplified by the button 200 and connected parts may be variously used either by itself to control regulated tension or in conjunction with the valve mechanism governed by the tracker vents T, T", T", and R, or in conjunction with the described crescendo mechanism comprising the pneumatic 38.

It is to be understood that the invention is not limited to the specific details of construction, organization and mode of operation hereinbefore described for purposes of illustration. On the contrary, the invention may be variously modified within the scope of the sub'oined claims as will appear to those skilled 111 theart.

I claim as my invention:

1. An instrument of the character described comprising, in combination, pneumatic playing actions; a main source of pneumatic power for operating said playing actions; expression-governing means for varying the transmission of said power to the playing actions; means controlling the expression-governing means for varying such transmission by substantially continuous progression at a plurality of difi'erent speeds; means controlling the expressiongoverning means for varying said transmission by substantially distinct increments; a tracker; and means connecting the tracker with said controlling means.

An instrument of the character described comprising, in combination, pneumatic playing actions; a'main source of pneumatic power for operating said playing actions; expression-governing means for varying the transmission of said power to the playing actions; a tracker; tracker controlled crescendo means operating upon said expression-governing means to vary such transmission by substantially continuous progression; means for operating said crescendo means at a plurality of different speeds; and tracker controlled means for varying the said transmission by substantially distinct increments, operable concurrently with said crescendo means.

3. An instrument of the character described comprising, in combination, pneumatic playing actions; a main source of pneumatic power for operating said playing actions; regulating means interposed between the main source of power and said playing actions to maintain uniformity of playing intensities whether one or many tones are sounded; a tracker; tracker controlled means connected to said regulating means forvarying the regulation thereby to produce substantially distinct increments of change of laying intensity; and concurrently operaiile tracker-controlled means connected to said regulating means for varying the regulation thereby,,by substantially continuous progression.

4. An instrument of the character described comprising, in combination, pneumatic playing actions; a main source of pneumatic power for operating said playing act-ions; a regulator inter osed between the main source of power an said playing actions; a tracker; tracker governed controlling means for the regulator causing the same to produce a plurality of different distinct degrees of playing intensity; and additional tracker-governed controlling means for the regulator for varying the regulation thereof by substantially continuous progression.

5. An instrument of the character described comprising, in combination, playing actions; a main source of pnuematic power for operating said playing actions; a regulator having a variable acting area and operatively connected to a valve interposed be tween the main source of power and the playing actions; controlling means for said regulator to vary the acting area thereof to produce diifierent degrees of playing intensities; controlling means for the regulator for producing crescendo effects; a tracker; and tracker controlled governing means for both said controlling means.

6. In an instrument of the character de scribed, the combination of pneumatic playing actions; a main source of pneumatic power for operating said playing actions: expression-governing means for varying the transmission of said power to the playing actions; controlling means for the expremiongoverning means for varying spch transmisits sion by substantially distinct increments; and crescendo apparatus,including a pneumatic acting on said controlling means; and means to control the crescendo apparatus.

7. In an instrument of the character described, the combination of a container for regulated pressure for operating the playing instrumentalities of the instrument; a source of high exhaust communicating with said container; expression-governing means for varying the communication between said container and said source of high exhaust; controlling means for said expression-governing means for varying such communication by substantially distinct increments; and crescendo and diminuendo apparatus, including a pneumatic acting upon said controlling means;means for establishing communication between said pneumatic and the source of high exhaust or atmosphere alternatively to produce a'crescendo or a diminuendo; and means to vary the communication between said pneumatic and the source of high exhaust or atmosphere to vary the speed of the crescendo or diminuendo.

8. In an instrument of the character described the combination of a tracker; a container for regulated-,pressrue for operating the playing instrumentalities of the instrument; a source of high exhaust communicating wit-h said container 'expression-governing means for Varying'the communication between said container. and the source of high. exhaust; means controlling said expression-governing means for varying said communication by substantially distinct increments; a pneumatic operatively connected to said expression-governing means; means for establishing communication between said pneumatic and the source of high exhaust or atmosphere altematively; means operable from the tracker for actuating said last named means; means to vary the communication between said pneumatic and the source of high exhaust or. atmosphere; and means operable from the tracker for actuating said last named means.

9. An instrument of the character described, comprising in combination, a tracker; pneumatic playing actions; a source of pneumatic' power for operating said actions; and an automatic crescendoproducing apparatus comprising a valve between said source of power and said actions controlling means for said valve to increase playing intensities at difl'erent speeds selectively; a music sheet having means to predetermine'the selection of the speed of such increaseiin intensity and also the extent of such increase at the selected speed; and means to produce changes of playing intensity by perceptible increments, said means and the crescendo producing mechanism being operable jointly or sever ally.

10. In a musical instrument, the combination of playing pneumatics; a source of power for operating said pneumatics; a crescendo bellows for causing progressional changes in playing intensities; a separate step pneumatic for causing incremental changes in playing intensities; a regulator pneumatic; a valve between said source of power and the playing pneumatics; and means for controlling said valve by the conjoined operation of said three pneumatics.

11. In a musical instrument, the combination of playing pneumatics; a source of power for operating said playing pneumatics; a crescendo pneumatic for causing progressional changes in playing intensities; a step pneumatic for causing incremental changes in playing intensities; a regulator pneumatic; a valve between said source of power and said playing pneumatics; connections from said valve to the regulator pneumatic; and means for modifying the action of said regulator bellows by said step bellows and crescendo pneumatics. V

12. In a musical instrument, the combination of playing pneumatics; a source of power for operating said playing pneumatics; a crescendo pneumatic for causing progressional changes in playing intensities; a step pneumatic for causing incremental changes in playing intensities; a regulator pneumatic; a valve between said source of power and said playing pneumatics; connections from said valve to the regulator pneumatic; connecting means between the crescendo pneumatic and step pneumatic; and transmission means between said connecting means and the regulating pneumatic for transmitting the ac tion of the crescendo and step pneumatics to the regulating pneumatic to modify the regulation by the latter.

13. In a musical instrument, the combination of playing pneumatics; a source or" power for operating said playing pneumatics; an automatically operable crescendo means operable at different speeds to produce crescendos and diminuendos of differ ent speeds; automatically operable stepchange-means to produce substantially disstinct steps of playing intensity, said step means being operable together with or separately from said crescendo means; a valve between said source of power and said playing pneumatics; a regulator pneumatic for controlling said valve; and means operatively connecting the regulator pneumatic with said crescendo means and said step means.

14. In a musical instrument, the combination of playing actions; a source of power for operating said actions; automatic crescendo means operable at moderate speed to produce gradual change in playing intensity; separate. automatic step means operable at high speed to produce substan tially instantaneous changes in playing intensity; a powercontrolling device between said source of power and said playing actions; regulating means governing the action of said power controlling means; and means for transmitting the joint or several operations of said crescendo means and step means to the said regulating means.

15. In a musical instrument, the combinationof playing pneumatics; a source of power for operating said playing pneumatics; a crescendo pneumatic having ducts of different capacities for operating'the crescendo pneumatic gradually at different speeds; a separate step pneumatic having means for operating the same substantially instantaneously and to different extents to produce various distinct steps of change in playing intensities; a valve between said source of power and said playing pneumatics; a regulator pneumatic controlling said valve; and means for governing said valve by said crescendo and step pneumatics conjointly with said regulating bellows.

16. In a musical instrument, the combination of playing pneumatics; a source of power for operating said playing pneumatics; a crescendo pneumatic having ducts of different capacities for operating the crescendo pneumatic gradually at different speeds; a separate step pneumatic having means for operating the same substantially instantaneous and to different extents to produce various distinct steps of change in playing intensities; a valve between said source of power and said playing pneumatics; a regulator pneumatic controlling said valve; and means for transmitting the action of said crescendo and step pneumatics to the regulator bellows.

17. In a musical instrument the combination of player pneumatics; a source of power for operating said pneumatics; a regulator having operative connection with a valve between the source of power and the playing pneumatics; a crescendo pneumatic for modifying the action of said regulator pneumatic to produce progressional changes in playing intensities; a step pneumatic for modifying the action of said regulatorto produce incremental changes in playing intensities; and means to operate said crescendo pneumat c and step pneumatics conjointly or independently of each other.

-18. In a musical instrument, the combination of playing pneumatics; a source of power for operating said playing pneumatics an automaticall operable crescendo means, operable atrdifi'erent speeds to produce crescendos and diminuendos at different speeds; automatically operable stepchange means, means to produce substantially distinct steps of playing intensity, said step-means being operable together with or separately from said crescendo means; a valve between said source of power and said playing pneumatics; a regulator pneumatic for controlling said valve; and means operatively connecting the regulator valve with said crescendo means and step means.

19. In a musical instrument, the combination of playing pneumatics; a source of power for operating said playing pneumatics; a regulator valve intermediate said source of power and said playing pneumatics; a regulator pneumatic operatively connected to said valve; a step-change pneumatic, and a crescendo pneumatic co-operatively connected to said regulator valve.

20. Expression governing means for an automatic musical instrument comprising, in combination, regulating means including a valve and a connected pneumatic for governing the flow of air from an action chest to a source of power to maintain uniformity of playing intensities, means to vary playing intensities in a certain characteristic manner, additional means to vary playing intensities in another characteristic mannor, a tracker, and tracker controlled means for operating said playing intensity varying means separatel or conjointly whereby the characteristic efl ect of either or the resultant effect of both may be impressed upon said regulating means.

21. Expression governing means for an automatic musical instrument comprising, in combination, regulating means including a valve and a connected pneumatic for governing the flow of air from an action chest to a source of power to maintain uniformity of playing intensities, a plurality of independently operable expression varying means having different characteristic efiects and both arranged to act upon said regulat ing means separatel or conjointly, a tracker, and tracker control ed means to operate said expression varying means.

22. Expression governing means for an automatic musical instrument comprising, in combination, regulating means including a valve and a connected pneumatic for governing the flow of air from an action chest to a source of power to maintain uniformity of playing intensities, expression varying means to vary playing intensities gradually,

expression var ing means to vary playing ation is effective to vary playing intensities.

23. Expression governing means for an automatic musical instrument comprising, in combination, regulating means including a by the resultant effect of their conjoint opervalve and a connected pneumatic for governing the flow of air from an action chest to a source of power to maintain uniformity of playing intensities, two expression devices operatively connected with said' regulating means, means to operate either one of said expression devices independently of the other to produce expression changes of different character or to operate said expression devices conjointly.

24. Expression governing means for an automatic musical instrument comprising, in combination, regulating means including a valve and a connected pneumatic for governing the flow of air from an action chest to a source of power to maintain uniformity of playing intensities, two expression devices both having operative connection with said regulating means, and means to operate one of said expression devices independently of the other to vary playing intensities in one characteristic manner, to operate the other said expression device independently of the former to vary playing intensities in another characteristic manner, or to operate said expression devices together to combine the characteristic variations of playing intensities produced by the independent operation of said expression devices.

25. Expression governing means for an automatic musical instrument comprising, in combination, regulating means including a valve and a connected pneumatic for governing the flow of air from an action chest to a source of power to maintain uniformity of playing intensities, two independently operable expression devices acting upon said regulating means, a tracker, tracker controlled means to operate one of said expression de vices to vary playing intensities for cre' scendo and diminuendo effects; and tracker controlled means to operate the other said expression device to produce step change effects in playing intensities.

In testimony whereof, I have signed my name to this specification this-26th day of April, 1920.

CHARLES .F. STODDARD.

Certificate of Qorreetiene It is hereby certified that in Letters Patent No. 1,409,181, granted March 14, 1922,

upon the application of Charles F. Stoddard, of New York, N. Y., for an improvement in Automatic Musical Instruments, errors appear in the printed specification requiring correction as follows: Page 11, lines 69, 88, and 89, claims 10 and 11, for the Word bellows read pnemna-tic, and line 90, for pneumatics read pneumatic; page 12-, lines 26 and 42, claims 15 and 16, for the Word bellows read pneumatic; and that the said Letters Patent should be read with these correc'tions therein that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 13th day of June, A. D, 1922.

[emu] KARL FENNING,

Acting Commissioner of Patents,

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,409,481, granted March 14, 1922, upon the application of Charles F. Stoddard, of New York, N. Y., for an improvement in Automatic Musical Instruments, errors appear in the printed specification requiring correction as follows: Page 11, lines 69, 88, and 89, claims 10 and 11, for the Word bellows read pneumatic, and line 90, for neumatics read pneumatic; page 12-, lines 26 and 42, claims 15 and 16, for the Word bellows read pneumatic; and that the said Letters Patent should be read with these corv rections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 13th day of June, A. D., 1922.

[SEAL] KARL FENNING,

Acting Gammz'ssioner of Patents. 

